1. Field of the Invention
The present invention relates generally to the field of electric machines, and more particularly to a three-phase connector for an electric vehicle drivetrain.
2. Background of the Invention
Phase connectors are connectors which carry current, for example, from the internally gated bipolar transistors (IGBT""s) of an inverter to an electric motor. The IGBT is the power transistor in the inverter and generates the sine wave for the three-phase current. It is not possible to simply thread the wires for the three phases through an opening in the electric motor housing because the current carried through the phase connections is very high, such as 350-400 amps. In carrying the three-phase current from the IGBT of the inverter to a three-phase induction motor, the three phases must remain isolated, and it is necessary to have some kind of connector which isolates the phases from each other.
Previously, three separate connectors were used to carry the three-phase current to the electric motor. FIG. 1 shows a cross-sectional view of such a prior art separate phase connector 2. All three separate connectors were required to isolate the electric current from the motor housing as it passed through from the inverter. With separate phase connectors, each of the three individual connectors carries a separate phase current through a separate opening in the motor casing and is fastened with a separate set of fasteners. Thus, separate phase connectors require many different parts and must each be individually bolted to the housings with separate holes drilled for each connector. The resulting package was large, costly, and required significant effort to assemble.
It is a feature and advantage of the present invention to provide a three-phase connector that carries all three phases in one connector, while keeping all the phases properly isolated from each other and from the motor case.
To achieve the stated and additional features, advantages and objects, an embodiment of the present invention provides a three-phase connector that carries all three phases in one connector and keeps all the phases properly isolated from each other and the motor case. The three-phase connector has three separate metal inserts which act as each phase carrying electrical current to a three-phase induction motor. The three inserts are all molded into one plastic housing, which reduces the size and cost of the part, and reduces the effort required to assemble the drivetrain.
An embodiment of the present invention provides a three-phase connector, for example, for an electric vehicle drivetrain, utilizing two or more, and preferably three electrically conductive connector components, that are spaced from one another and supported in an over molding of electrically insulating material covering each of the connector components, except for upper and lower exposed ends of the connector components, and also forming a supporting flange. First and second ones of the connector components are spaced farther apart from one another than they are from a third connector component that is disposed, for example, between them. The first and second connector components extend above the flange with their respective exposed upper ends offset in different planes than the exposed upper end of the third connector component. The first and second connector components also extend below the flange with their respective exposed lower ends disposed in different planes than the third connector component.
In addition, the upper exposed ends of the first and second connector components are disposed a different and preferably shorter distance above the flange than the exposed upper end of the third connector component, and the respective lower exposed ends of the first and second connector components are disposed a different and preferably greater distance below the flange than the exposed lower end of the third connector component. Further, each of the connector components has an upper portion that extends a pre-defined distance above the flange and a lower portion that extends a greater distance below the flange than the pre-defined distance above the flange.
An electrically insulating material, such as nylon, is used for the over molding, and each connector component is made of an electrically conducting metal, such as tellurium copper, that is machined and over molded with the electrically insulating material. Each connector component is drilled at its upper and lower ends and tapped internally to receive a threaded bolt, for example, for a busbar or a lead. Each connector component has an exterior wall with one or more undercuts that provide an anchor for the over molding material. The flange is provided with openings to receive fasteners for attaching the flange to a housing. An alternate embodiment includes, for example, partitions formed by the over molding that extend upward from the flange between each of the first and second connector components and the third connector component.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become more apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention.